1) Unmyelinated somatic afferent C and myelinated A-delta nociceptive nerve fibers have different physiological and psychological functions in humans. C fiber is associated with chronic pain and has a strong affective component. A-delta fiber is associated with acute pain and escape responses. The forebrain mechanisms that mediate these different functions are unknown. We will use quantitative functional brain imaging and psychophysical measurements in normal subjects and patients with neuropathic pain to reveal the forebrain circuits that mediate these functions. 2) My previous study has employed electroencephalography (EEG) and magnetoencephalography (MEG). These techniques have milliseconds temporal resolution, but largely limited to the study of early cortical responses. A more comprehensive investigation of cerebral pain mechanisms requires the use of brain imaging method that allow measurement across a broader range of cortical and subcortical structures. Thus, I seek additional training in (i) Technique: Functional magnetic resonance imaging (fMRI) with spatio-temporal resolutions of millimeters and seconds to minutes. (ii) Theory: Develop a new understanding the neurobiology of the affective-emotional aspect of pain, which directly relates to chronic pain. 3) General aims: (i) To master the new technique, which will enable me to integrate various technologies in investigating sensory discriminative and affective-emotional aspects of pain. (ii) To develop the technical and theoretical foundation necessary for an independent investigator. (iii) To facilitate my future international cooperation and to become a leading neuroscience researcher in Vietnam.